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jwri37_02_019
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論文情報
タイトル
Optical Interaction between Laser Beam and Induced Plume in the Ultra-High Power Density Fiber Laser Welding of Stainless Stee
著者
Kawahito, Yousuke
Kawahito, Yousuke
Mizutani, Masami
Mizutani, Masami
Katayama, Seiji
Katayama, Seiji
キーワード等
High-power fiber laser
Laser-induced plume
Stainless steel
high-speed observation
Spectroscopic analysis
Laser probe measurements
抄録
The objective of this research is to obtain a fundamental knowledge of the optical interactions in a 10-kW fiber laser beam of 0.9-MW/㎟ power density and the plume or plasma induced during bead-on-plate welding of 20-mm-thick Type 304 stainless steel plate, on the basis of high-speed video observations, spectroscopic analysis and laser probe measurements. According to the high-speed observation results, the laser-induced plume was repeatedly generated from a keyhole at intervals of about 0.5-ms. The spectroscopy indicated that a bright plume emitted the line spectra of neutral atoms of alloying elements in Type 304 such as iron (Fe), chromium (Cr) and manganese (Mn). The temperature and the ionization degree of the laser-induced plume were calculated to be approximately 6,000 K and 0.02, respectively, by the Bolzman plots and via Saha’s equation. Furthermore, the probe laser passed horizontally through the plume was refracted at 0.6-mrad angle on average, which was much lower than the 90-mrad divergence of the focused fiber laser beam. The attenuation of the probe laser was measured to be about 4%, which was not mainly caused by Inverse Bremsstrahlung but by Rayleigh scattering. Subsequently, a stable laser welding process could be established at such an ultra-high power density that 11.5-mm-deep penetration was obtained even if the laser peak power was modulated 1-ms-periodically from 10 kW to 8.5 kW. It was consequently considered that the optical interaction between the 10-kW fiber laser beam and the weakly-ionized plume was too small to exert a reduction in weld penetration.
公開者
大阪大学接合科学研究所
公開者の別表記
Joining and Welding Research Institute, Osaka University
公開者 (ヨミ)
オオサカ ダイガク セツゴウ カガク ケンキュウジョ
掲載誌名
Transactions of JWRI
巻
37
号
2
開始ページ
19
終了ページ
25
刊行年月
2008-12
ISSN
03874508
NCID
AA00867058
URL
http://hdl.handle.net/11094/5073
言語
英語
カテゴリ
紀要論文 Departmental Bulletin Paper
Transactions of JWRI / Vol.37 No.2 (2008-12)
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著者版フラグ
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text
DCTERMS.bibliographicCitation
Transactions of JWRI.37(2) P.19-P.25
DC.title
Optical Interaction between Laser Beam and Induced Plume in the Ultra-High Power Density Fiber Laser Welding of Stainless Stee
DC.creator
Kawahito, Yousuke
Mizutani, Masami
Katayama, Seiji
DC.publisher
大阪大学接合科学研究所
DC.language" scheme="DCTERMS.RFC1766
英語
DCTERMS.issued" scheme="DCTERMS.W3CDTF
2008-12
DC.identifier" scheme="DCTERMS.URI
http://hdl.handle.net/11094/5073
DC.subject
High-power fiber laser
Laser-induced plume
Stainless steel
high-speed observation
Spectroscopic analysis
Laser probe measurements
DCTERMS.abstract
The objective of this research is to obtain a fundamental knowledge of the optical interactions in a 10-kW fiber laser beam of 0.9-MW/㎟ power density and the plume or plasma induced during bead-on-plate welding of 20-mm-thick Type 304 stainless steel plate, on the basis of high-speed video observations, spectroscopic analysis and laser probe measurements. According to the high-speed observation results, the laser-induced plume was repeatedly generated from a keyhole at intervals of about 0.5-ms. The spectroscopy indicated that a bright plume emitted the line spectra of neutral atoms of alloying elements in Type 304 such as iron (Fe), chromium (Cr) and manganese (Mn). The temperature and the ionization degree of the laser-induced plume were calculated to be approximately 6,000 K and 0.02, respectively, by the Bolzman plots and via Saha’s equation. Furthermore, the probe laser passed horizontally through the plume was refracted at 0.6-mrad angle on average, which was much lower than the 90-mrad divergence of the focused fiber laser beam. The attenuation of the probe laser was measured to be about 4%, which was not mainly caused by Inverse Bremsstrahlung but by Rayleigh scattering. Subsequently, a stable laser welding process could be established at such an ultra-high power density that 11.5-mm-deep penetration was obtained even if the laser peak power was modulated 1-ms-periodically from 10 kW to 8.5 kW. It was consequently considered that the optical interaction between the 10-kW fiber laser beam and the weakly-ionized plume was too small to exert a reduction in weld penetration.
citation_title
Optical Interaction between Laser Beam and Induced Plume in the Ultra-High Power Density Fiber Laser Welding of Stainless Stee
citation_author
Kawahito, Yousuke
Mizutani, Masami
Katayama, Seiji
citation_publisher
大阪大学接合科学研究所
citation_language
英語
citation_date
2008-12
citation_journal_title
Transactions of JWRI
citation_volume
37
citation_issue
2
citation_firstpage
19
citation_lastpage
25
citation_issn
03874508
citation_public_url
http://hdl.handle.net/11094/5073
citation_keywords
High-power fiber laser
Laser-induced plume
Stainless steel
high-speed observation
Spectroscopic analysis
Laser probe measurements